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Radiotherapy to the cerebellum for children

This page has been written to give you general information and answer some of the questions you may have about the side effects of radiotherapy.

We hope you will find this helpful.

Introduction

The cerebellum is the back, lower part of the brain and lies just above the back of the neck and behind the ears. This area is sometimes referred to as the “posterior fossa”. More than half of all children’s brain tumours occur here. Medulloblastoma, ependymoma, and gliomas are the commoner ones.

We give radiation treatment (radiotherapy) after surgery because the disease is likely to come back if we do not. The treatment has to be planned with great care and it is successful for many but unfortunately not all patients. Your consultant will talk to you about this.

The total radiation dose has to be spread out over quite a long time to make the individual treatments safe. We give treatment every day for about six weeks (usually excluding weekends and bank holidays). At each session, the patient spends about ten minutes in the treatment room but most of this time is spent getting him/her into the right position.

Radiotherapy does not hurt, the machine does not touch the patient and it is rather like having an ordinary x-ray. We have to treat the whole area accurately, which means that the patient must lie very still on their front. To make this easier, we make a facemask for each patient. Lying still can be very difficult for some children, particularly young ones, so occasionally we have to use a general anaesthetic.

Occasionally when we are treating the brain, a blue light is seen and there might be a strange smell. Also a buzzing noise can be heard which is the machine working.

Side effects

There are always side effects. We can relieve most of them but sometimes not completely. Some of the side effects happen immediately, some of them happen soon after we finish treatment and some take a longer time to show.

Immediate side effects

Sometimes the treatment causes the brain to swell slightly (at its greatest about ten days into treatment). This is usually not noticeable because pressure on the brain has been eased by removing the tumour or relieving it with a shunt (a pressure relieving device). If swelling causes problems we give a small dose of steroids.

We cannot prevent patients losing their hair in the area being treated. It starts to fall out after about two weeks of treatment and is more or less gone by the end. It usually starts to grow back about three months after treatment though sometimes hair doesn’t fully grow back.

Nausea and vomiting are uncommon with this treatment.

Side effects after completing treatment

A long course of radiotherapy makes patients tired. This is most noticeable near the end of the treatment and just afterwards. There might be a particularly sleepy spell starting four to six weeks after treatment ends and going on for two to six weeks or even longer.

There may be occasional headaches or bouts of sickness.

These side effects can be very worrying at the time but they usually all settle down within about three months.

Long-term side effects

These are the hardest to predict and unfortunately, when they do happen, they are permanent.

Young children will not be quite as tall as they would have been. The radiation can affect the gland that controls growth (the pituitary gland). Also, the radiation will affect the bones at the top of the neck and they do not grow as they would have done. Growth hormone can improve things. However, a young child may be very slightly shorter when grown-up than without the illness and treatment.

The pituitary gland also controls development. Radiotherapy for children may make puberty start earlier. Endocrinologists (doctors specialising in hormones) will help deal with any problems.

It is possible for radiotherapy to affect learning ability, especially when very young children’s brains are treated. However the smaller the area treated the less likely there is to be a problem. We are finding that by three or four years after treatment young children don’t learn new information and skills quite as easily. We need to know exactly what the effects are and how we can support and help people who have been affected. When it is possible, one of our neuropsychologists will see the patient before treatment starts and yearly afterwards.

We are finding that, very rarely, children who have had treatment for one tumour can develop another type of tumour some years later.